The Château de Tours was built in the 11th century. The building displayed an architecture of the Carolingian period, and was the residence of the Lords of France. Until the 2000s, the Royal Castle of Tours was used as an aquarium where about 1,500 fish of 200 different species could be seen. It also served as Grévin museum. The castle was classified as monument historique on 20 August 1913.
Currently, the building houses contemporary exhibitions of paintings and photographs, including works by Joan Miró, Daniel Buren,Nadar, and the workshop of Tours history where archaeological and historical documents, models, audio-visual films on the history of Tours, etc, are shown.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.